Why can a ball bearing be attracted to each side of a magnet? When the ball bearing is at the north pole of a magnet, it seems to become a south pole, but when its at a south pole, it seems to become a north pole and hence, can become attracted to either pole of a magnet. Also, what determines which pole the ball bearing becomes? Is it the pole that's closest? For instance, I suspended a ball bearing exactly between two different magnetic poles, which one would it be attracted to and why?
closed as unclear what you're asking by Jon Custer, Sebastian Riese, AccidentalFourierTransform, glS, ZeroTheHero Jul 17 '18 at 6:40
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Ball bearings on their own do not generate magnetic fields, but when placed in a magnetic field the spins align with it and it becomes an induced magnet. If held near the north pole the spins will align so that the nearby part of the bearing acts as a south pole and the remote part of the bearing as a north pole, and the whole bearing will be attracted. The same happens with reversed polarity near the south pole of the magnet.
A ball bearing is made of a ferromagnetic material - steel.
Assume first that the ball bearing is not magnetised.
Then bringing a magnet close to the ball bearing will induce magnetism into the ball bearing such that the induced pole on the ball bearing is of the opposite type to the pole of the magnet which is closest to the ball bearing.
So you get unlike pole attracting because the repulsive force between the same pole induced on the ball bearing is further from the inducing pole on the magnet.
It is highly likely that the process described above will induce permanent magnetism in the ball bearing so it too will have a north and a south pole.
If now you separate the ball bearing and the magnet and then bring the magnet slowly up to the ball bearing it is possible for the magnetised ball bearing to be repelled by the magnet because the same poles are facing each other.
So it will not always be the case that you get attraction between a ball bearing and a magnet.
However if the magnet is brought close enough you will get attraction because the inducing magnetic field due to the magnet is strong enough to reverse the initial magnetism of the ball bearing to make the force between thenm attractive.
For instance, I suspended a ball bearing exactly between two different magnetic poles, which one would it be attracted to and why?
That position is one of unstable equilibrium and the smallest perturbation to the position of the steel ball bearing would result in the ball bearing being attracted to one of the poles of the magnet.